Timing of Eyewitness Expert Testimony, Jurors' Need for Cognition, and Case Strength as Determinants of Trial Verdicts.

In 2 experiments, college students read a murder-trial transcript that included or did not include court-appointed expert testimony about eyewitness memory. The testimony either preceded or followed the evidence, and the judge's final instructions reminded or did not remind jurors about the expert's testimony. Expert testimony decreased perceptions of guilt and eyewitness believability when it followed the evidence and preceded the judge's reminder. This effect occurred whether the prosecution case was moderately weak or moderately strong. Jurors' need for cognition (NC) was curvilinearly related to convictions in a strong case. Low and high NC jurors convicted less than did moderate NC jurors. Greater scrutiny by high NC jurors may make them more likely to consider evidence for the weaker side.